Supporting Figure 4

In-plane XRD view of the few layer (6.25 nm) WS2 film grown on 1000 oC annealed substrate (a); corresponding 3D-RHEED plan view of the single layer WS2 film (b). The yellow circles on (a, b) depict the corresponding nodes of model reciprocal lattice of WS2. One can note the difference in the field of view between XRD and 3D-RHEED. The XRD gives a high- resolution image of the central part, while 3D-RHEED allows capturing the data over wider region of reciprocal space. The 0o orientation of the film is clearly seen in both pictures.